/**
 * Copyright The Apache Software Foundation
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package com.alibaba.tac.engine.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Utility methods for Iterable including null-safe handlers.
 */
public class IterableUtils {

  private static final List<Object> EMPTY_LIST = Collections
      .unmodifiableList(new ArrayList<Object>(0));

  @SuppressWarnings("unchecked")
  public static <T> Iterable<T> nullSafe(Iterable<T> in) {
    if (in == null) {
      return (List<T>) EMPTY_LIST;
    }
    return in;
  }

}